Valves are commonly used in devices that involve the transportation of a fluid. A typical type of valve, for example used in laboratory systems of moderate sizes, is the rotary valve.
Generally, a rotary valve has a stationary body, herein called a stator, which co-operates with a rotating body, herein called a rotor. The rotor can be moved from one working position to another working position by hand or by an actuator such as an electric motor.
In general, the stator has a stator body which is provided with a number of inlet and outlet ports connectable to liquid supplies and components which are to be supplied with the liquids, and an end surface with an inner stator face. The ports are in fluid communication with a corresponding set of orifices and/or grooves on the inner stator face via bores in the stator body. The inner stator face is part of the surface of the stator that is in fluid-tight contact with an inner rotor face of the rotor. The rotor is typically formed as a disc and the inner rotor face is pressed against the inner stator face and able to rotate around a, normally central, axis of rotation with respect to the inner stator face. The inner rotor face is provided with one or more grooves and/or orifices which are connected by bores in the rotor body. These grooves and/or orifices can interconnect different orifices and/or grooves on the stator depending on the angular position of the rotor around the axis of rotation with respect to the stator.
Rotary valves can be designed to withstand high pressures (such as pressures above 25 MPa). They can be made from a range of materials, such as stainless steel, high performance polymeric materials and ceramics.
The number of inlets/outlets as well as the design of grooves and bores in the rotor and the stator reflect the intended use of a specific valve. A common type of multi-purpose valve has one stator inlet port, placed in the axis of rotation of the rotor of the valve, and a number of outlets ports that are placed equidistantly around the inlet port. The rotor has a single, radially extending groove that has one end in the axis of rotation of the rotor, thereby always being connected to the inlet port of the stator, while the other end can be connected to any one of the outlets by choosing the appropriate the angular position of the rotor with respect to the stator. Such a valve is useful to direct a flow from the inlet to any of the outlets—but only to one outlet at a time.
In many systems, for example, chromatography systems for continuous chromatography, a large number of valves are used for providing two different solutions (e.g. a feed and a buffer) to the different components (e.g. chromatography columns) in the system in the correct order and to guide the solutions leaving the components (e.g. an eluate—the solution of buffer and dissolved matter resulting from elution—and an used feed) to the correct destinations. There is a need for better valve arrangements in such systems.